<!doctype html> 
<html> 
<head> 
    <meta charset="utf-8"> 
    <title></title> 
</head>
<body>
<script type="text/javascript">

String = Number;
var a = new String(1);
//'1'+1
//1+1
//alert(typeof a);
alert(a+1);
//String = null;
//Array = null;
//Number = null;
//Object = null;
//var a = '123';
//var a = new String('abc');
//var a = new Number(1);
//alert(a);

</script>
</body>
</html>